Many people require eyewear to improve or facilitate vision. While there are surgical procedures available to correct some vision problems, and contact lenses as well, these approaches are not always satisfactory for every condition. As a result, there is a variety of different types of eyewear available. The eyewear may be used for a number of reasons including but not limited to correcting vision issues. Eyewear may also be required to protect the eye from damage or injury. In some instances, the eyewear may be desired for fashion or aesthetic reasons.
The eyewear may include one or more lenses secured to each other or to a frame. In addition to the eyewear, which may be denominated a primary lens assembly, there may also be a secondary lens assembly used in conjunction with the primary lens assembly. The secondary lens assembly may be desired for a variety of reasons. One reason for using a secondary lens assembly may be to reduce sun glare. Another reason may be to protect the eyes from damage or injury. Another reason may be to avoid the expense of progressive lenses. Progressive lenses resolve a number of vision issues in a single lens. Thus, there can be one portion of the lens that permits reading or a other section of the lens for distance viewing. There may also be lenses that provide both types of correction to a user's eyes in a single lens. While the progressive lenses solve many problems for wearers, they are still not satisfactory for everyone. Some people have issues with the costs of the lenses. Others are concerned with their ability to see clearly under a variety of conditions. Where the progressive lens is small in size because the user wants the glasses to have as minimal a visual impact on their looks as possible, the users' ability to see out of the progressive lens can be compromised. Because there is a smaller viewing area for the eye to see through for each area of the lens in a small progressive lens, there have been complaints from users that it is not easy to use certain regions of the lenses. Thus, a user may opt to avoid the progressive lenses and use a secondary lens over the primary lens when necessary.
Other users like the convenience of a secondary set of lenses over a primary set of lenses. This permits a user to have the comfort and ease of use of the primary lenses coupled with a secondary set of lenses for situations where the attributes of the second set of lenses are desirable such as for sun glare, etc.
The secondary lens assembly may be positioned in front of the primary lens assembly or it may be behind the primary lens assembly as shown in U.S. Pat. No. 7,370,961, the disclosures of which are incorporated herein by reference.
While in some instances the secondary lens assembly may be merely clipped on the front of the primary lens assembly, there are also a number of other approaches for securing the secondary lens assembly to the primary lens assembly. These can be seen in U.S. Pat. No. 6,811,254 to Ifergan, U.S. Pat. No. 6,116,730 to Kwok, U.S. Pat. No. 6,109,747 to Chao, U.S. Pat. No. 6,012,811 to Chao and U.S. Pat. No. 6,939,003 to Kidouchin, the disclosures of which are incorporated herein by reference.